Clutchless mechanical gear transmission

Abstract

A transmission apparatus for changing the speed of a driven member relative to the speed of a driving member without interrupting the torque transfer between the members. The apparatus includes reducing gears driven by a driving member, annular cam gears in continuous engagement with the reducing gears, and a driven member which journals the cam gears for rotation. One section of the driven member is hollow and has a plurality of radially extending apertures each containing a reciprocating detent for engaging an inner cam surface or a corresponding cam gear. A shift member mounts within the bore of the driven member and moves along the rotational axis of the driven member to cause the detents to reciprocate between a cam gear engaged position and a disengaged position. By timing the movement of the shift member and the design of the cam surfaces on the cam gear, one cam gear can be simultaneously engaged while another is being disengaged to produce a gear ratio change without interrupting torque transfer between the driving and driven members.

What is claimed is: 
     
       1. A transmission apparatus for changing the speed of a driven member relative to the speed of a driving member, said apparatus comprising: a plurality of reducing gears;   driving means for causing said reducing gears to move in response to movement of said driving member;   a plurality of annular cam gears each in continuous driving engagement with a corresponding one of said reducing gears, each of said cam gears having an inner cam surface with at least one peak and at least one, valley;   a hollow drum mounted for rotation about an axis and having a plurality of apertures extending from an inner drum surface to an outer drum surface, at least one of said apertures corresponding to each of said cam gears, and said cam gears being mounted for rotation about said outer drum surface with said inner cam surface opposite to said at least one corresponding aperture;   a plurality of detents, one corresponding to each of said drum apertures and each arranged for reciprocating radial movement within its corresponding drum aperture;   a cam member mounted within said drum for reciprocal axial movement back and forth along said drum axis, said cam member comprising an outer cam surface having a central portion extending radially for respectively engaging said detents to hold the engaged detent in a first position at which it engages the valley of the corresponding cam gear, end portions on either side of said central portion for allowing the engaged detent to move into a second position out of engagement with the peak of the corresponding cam gear, and intermediate portions on either side of said central portion for causing said detentes to reciprocate between said first and second positions in response to axial movement of said cam member; and,   actuating means for selectively moving said cam member in either axial direction relative to said drum so as to cause a selected detent to engage the valley of its corresponding cam gear such that a driving connection is made between said driving member and said driven member through said engaged cam gear, the inner cam surface of said cam gears and the outer cam surface of said cam member being contoured relative to each other to time the axial movement of said cam member such that said axial movement may commence only about when the peak of a cam gear to be disengaged from its corresponding detent is substantially aligned with the valley of an adjacent cam gear to be engaged by its corresponding detent, and said axial movement may cease only about when the valley of the cam gear to be disengaged is substantially aligned with the peak of the adjacent cam gear to be engaged.   
     
     
       2. A transmission apparatus according to claim 1 which comprises three of said apertures and three of said detents corresponding to each of said cam gears, and wherein the inner cam surfaces of each of said cam gears comprises three of said valleys and three of said peaks.